Fibromyalgia (FM) is the most common chronic pain condition presenting with widespread musculoskeletal pain. These patients also have much comorbidity including fatigue, cognitive dysfunction, sleep difficulties, stiffness, depression and anxiety. FM is the third most common rheumatic disorder after low back pain and osteoarthritis. Currently it is estimated that fibromyalgia affects an estimated 12-15 million people in the U.S. and about 3-6% of the world population. Currently, the diagnosis of FM is based on the 1990 ACR classification criteria. These criteria require the simultaneous finding of two features: (1) a history of pain of at least 3 months in duration involving 3 or more quadrants of the body, including axial pain in the neck or low back or anterior chest, and (2) eleven or more out of 18 diagnostically standardized tender points palpated with a force of 4kg. There is currently no laboratory or imaging investigations that are associated with a definitive diagnosis of fibromyalgia as per the 1990 ACR criteria. In this current proposal we aim to establish a preliminary proof of concept that posits a unique gene expression signature obtained from the peripheral blood cells of FM patients using whole genome DNA microarrays. The finding of such gene networks would be the first evidence that there are indeed surrogate biomarkers for FM. Such a discovery could be informative for a blood based diagnosis, serial monitoring which can help alter therapies, the identification of biologically based clinical subgroups, the identification of genes/proteins involved in pathogenesis and the following of beneficial therapeutic responses to therapy. Confirmation of this hypothesis would be a paradigm shift from the current diagnosis of fibromyalgia and would establish a molecular basis for diagnosis and new therapies that does not exist currently.